Preheat oven to 350°F. Line a 12-cup muffin tin with muffin liners and set aside.
In one bowl, mix together cocoa powder, flour, sugar, baking soda, baking powder, and salt.
Mix in eggs, milk, canola oil, and vanilla extract.
Divide batter evenly among muffin cups and bake for 20 minutes or until a toothpick comes out clean.
Remove muffins from tins and allow to cool completely on a wire rack.